Heidelberg Pharma AG announced that initial clinical data from two Antibody Drug Conjugates (ADCs) based on the Company's proprietary ATAC technology was presented at the ASH Annual Meeting 2022. Heidelberg Pharma showed preliminary safety data from the clinical trial with its candidate HDP-101 and partner Magenta Therapeutics, Cambridge, MA, USA, (Magenta) presented in an oral session preliminary positive safety and initial efficacy data from its clinical trial with the ATAC candidate MGTA-117. HDP-101, an ATAC targeting BCMA, is currently being evaluated in an open-label, multi- center Phase I/IIa trial in patients with multiple myeloma, a bone marrow cancer with high unmet medical need.

The first part of the trial is a Phase I dose escalation study to determine an optimal and safe dose of HDP-101 for the Phase II part of the study. Preliminary results from the first two patient cohorts showed good tolerability. Currently, the trial is enrolling patients in cohort 3. MGTA-117 is being tested in a Phase I/II dose-escalation trial in relapsed/refractory (R/R) acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).

Patients with these conditions are deemed ineligible for transplant due to active disease characterized by high numbers of cancer blast cells present in the bone marrow and in the bloodstream. MGTA- 117 is designed to deplete these cancer cells prior to a stem cell transplant or to receiving an ex vivo gene therapy product. Preliminary results from 15 patients across three dose- escalation cohorts showed target cell depletion in the blood and bone marrow, providing evidence of an active dose.

Two transplant-ineligible patients became transplant-eligible due to the successful depletion of bone marrow cancer cells. MGTA-117 was well-tolerated in all participants. No serious adverse events were deemed to be related to MGTA-117; it cleared quickly as designed and no dose-limiting toxicities were observed.